The invention relates to a method of copolymerizing ethylene and up to 50 weight percent of an alphamonoolefin at temperatures between 200.degree. C. and 300.degree. C. under pressures up to 50,000 psig for a time of less than 10 minutes to produce low density polyethylene having a density of between 0.91 and 0.93 g.cc.
Tornquist, U.S. Pat. No. 3,010,787, relates to a method of preparing crystalline titanium catalyst by intensive grinding of a mixture of finely divided aluminum powder with titanium tetrachloride. This catalyst was used for low temperature polymerization of propylene.
Yokoyama et al, U.S. Pat. No. 4,146,502, teaches a catalyst component made by grinding a magnesium halide, an electron donor compound, and a titanium halide and then treating the resulting mixture with an interhalogen compound, such as iodine trichloride. The resulting component was used with an alkyl aluminum component to polymerize propylene at temperatures of between 30.degree. and 120.degree. C.
Giannini et al, U.S. Pat. No. 4,149,990, teaches the preparation of a catalyst component comprising magnesium halide, an electron donor having a reactive hydrogen atom, a titanium halide, and an electron donor free of reactive hydrogen atoms for use in polymerizing propylene at temperatures between 0.degree. and 150.degree. C.
Kaus et al, U.S. Pat. No. 4,347,158, teaches the use of at least two electron donors with a magnesium halide and an aluminum halide to polymerize propylene at 70.degree. C. and low pressures.
Jorgensen et al, U.S. Pat. No. 4,349,648, teaches the use of a catalyst comprised of a magnesium compound, a titanium compound, an electron donor and a cocatalyst consisting of alkyl aluminum compound to continuously prepare ethylene copolymer in gas phase at temperatures between 30.degree. and 105.degree. C. and a pressure not greater than 1000 psig.
None of the above references teach how to copolymerize alpha olefins with ethylene to prepare linear low density polyethylene at high temperature (&gt;200.degree. C.) and pressures (to 50,000 psig).